Field of Invention
Various embodiments of the present disclosure relate to a communication method using MIMO (Multiple Input Multiple Output) technology, and more particularly, to a communication method using MIMO technology to identify the number of users of a base station cell that changes continuously in order to allocate an optimal number of pilot signals, and a communication apparatus using the same.
Description of Related Art
Aggregated MIMO technology is generally used in a downward link mobile communication. In a base station using aggregated MIMO technology, a lot of antennas are installed. When a lot of antennas are installed in a transmitting end, a channel may be expressed in a very large random vector or matrix, wherein as the number of antennas increases infinitely, the random vector or matrix converge to a deterministic vector or matrix.
That is, the fading effect that occurs in an actual wireless communication environment may disappear. Furthermore, when a beamforming is performed using a lot of antennas in a transmitting end, a very small beam width will be formed. Therefore, the interference between terminals will decrease, and in an ideal case, the interference will converge to zero (0). When using the aggregated MIMO technology, the problem of interference and fading will both be solved, and thus it will be possible to stably transmit a lot of data through a wireless channel at a very high transmission rate.
However, the aggregated MIMO technology has a limitation that exact channel information cannot be obtained due to frequency reuse of base stations. A pilot signal from inside another base station may be received in a current base station, and such a pilot signal from outside may interfere with a pilot signal received from a terminal inside the current base station, thereby leading to a problem where the terminal inside the current base station cannot obtain a perfectly exact channel information of a desired terminal.